What's the script with mash volumes?

[ScottM]

I'm working on a little spreadsheet to work out some stuff, but I can't get my head around the mash volumes.

Ok say I want a final volume of 23L. I know that I lose 10L to boiling, deadspace, grains, hops, etc, etc, etc.

This gives me a starting volume of 33L.

From what I understand the mash volume and the sparge volume are generally quite similar, so the mash volume would be approx 16.5L and the sparge volume would be approx the same.

What I don't get is that most people recommend a mash volume of 2.5L/kg.

If I'm using 4kg of pale malt then that's only 10L.

Is that right that I should mash with 10L and sparge with 23? Seems to go against what people recommend while googling around.

Cheers

 

[pittsy]

2.5L per 1kg is 12.5 litres of water for 5kg batch , i aim for 3L per 1kg so i mash with 5kg and 15 litres of water

 

[rpt]

I do BIAB so I don't do a separate sparge but I keep reading to mash with 2.5L/kg and then sparge with 7.5L/kg.

 

[ScottM]

2.5L per 1kg is 12.5 litres of water for 5kg batch , i aim for 3L per 1kg so i mash with 5kg and 15 litres of water

Yeah I understand that part but how do you know how many L per kg to go with?

One of the recipes I read had a 14lb grain bill (6kg+). I'm guessing it's so large due to the grain bill having a low-ish yield. It was said that the mash ratio was 1.25qts/lb (or something like that) which I believe equates to approx 2.5L/kg.

Various calculators I have checked use the same figure (1.25qts/lb) or allow you to change the figure manually.

When mashing with a low weight/high yield grain bill such as pilsner malt, should I be adjusting the 2.5L/kg ratio to something a bit higher? Or do I leave it at 2.5L/kg and sparge twice?

 

[ScottM]

I do BIAB so I don't do a separate sparge but I keep reading to mash with 2.5L/kg and then sparge with 7.5L/kg.

Yeah I don't understand the reasoning for this. I can only assume that it takes the 2.5L/kg as gospel, regardless of grain bill.

Perhaps that is the case, and that is in fact what is meant to be done, but I like to get my head around these things

 

[oz11]

Batch sparge or fly sparge? For batch: Have you seen this?

 

[ScottM]

Have you seen this?

Yes, I don't have an issue with calculating what the sparges are etc.... I'm trying to get an understanding behind the figures and, in particular, the 2.5l/kg thing.

I like to understand how things work and where theories come from (Engineer)


Edit: Specifically...

It says next to the 2.5l/kg "Enter the Water/Grain ratio you will use for the mash in L/kg, e.g. 2.5L/kg"

How do I know what the water/grain ratio should be?

 

[oz11]

Okay try this one. It's not in new-fangled litres and kilograms tho :wha:

The thickness of the mash determines the quality of wort produced. 2.5L/gk is a figure that's often quoted as a reasonable starting point.

 

[oz11]

There is more light reading here

 

[ScottM]

Now you're talking

Makes more sense to me now. Having read the above I'm surprised most people stick with the 2.5L/kg, I would be more inclined to go with 3.5+.

Ideal, cheers :)

 

[zgoda]

I don't measure mash thickness, I just use as much water as I need for my brew length. This is usually 31 ltr for 21 ltr into bucket but it varies with amount of grains I use (less grains, less water). Today I'll use 28 ltr because I'm brewing low gravity mild and brew length is 19.5 ltr into bucket.

 

[ScottM]

I don't measure mash thickness, I just use as much water as I need for my brew length. This is usually 31 ltr for 21 ltr into bucket but it varies with amount of grains I use (less grains, less water). Today I'll use 28 ltr because I'm brewing low gravity mild and brew length is 19.5 ltr into bucket.

Yeah that's pretty much what I'll be doing as I'm going down the BIAB route. I just wanted to make the calculator complete :)

 

[zgoda]

The thickness is related to mash technique one employs in the brewhouse. German style heated mash tuns require stirring, so thin mashes are preferred, 3.5:1 up to 4.5:1 water-to-grain ratio. British style mashing doesn't require stirring, so thicker mashes are preferred to get equal mashing conditions in the whole tun.